Maternal Age Risks
Although it is possible for a woman of any age to have a baby with a chromosome abnormality, the chance increases as you age. Screening tests, such as serum integrated screening, sequential integrated screening, and quad screening, consider your age when estimating the chance for you to have a baby with a chromosome abnormality. This means that the chance for you to receive a "screen positive" result increases as you get older.
The following chart shows the approximate chances of having a baby with any chromosome abnormality, and the chance for Down syndrome:
|
Mother's age at
|
Approximate chance for any chromosome abnormality at birth
|
Approximate chance for Down syndrome at birth
|
|
15 |
1/450 |
1/1000 |
|
16 |
1/475 |
1/1100 |
|
17 |
1/500 |
1/1250 |
|
18 |
1/525 |
1/1425 |
|
19 |
1/550 |
1/1650 |
|
20 |
1/525 |
1/1650 |
|
21 |
1/525 |
1/1650 |
|
22 |
1/500 |
1/1650 |
|
23 |
1/500 |
1/1425 |
|
24 |
1/475 |
1/1250 |
|
25 |
1/475 |
1/1250 |
|
26 |
1/475 |
1/1100 |
|
27 |
1/455 |
1/1000 |
|
28 |
1/435 |
1/1000 |
|
29 |
1/420 |
1/900 |
|
30 |
1/385 |
1/900 |
|
31 |
1/385 |
1/800 |
|
32 |
1/325 |
1/725 |
|
33 |
1/285 |
1/600 |
|
34 |
1/250 |
1/465 |
|
35 |
1/200 |
1/365 |
|
36 |
1/165 |
1/285 |
|
37 |
1/125 |
1/225 |
|
38 |
1/100 |
1/175 |
|
39 |
1/80 |
1/140 |
|
40 |
1/65 |
1/110 |
|
41 |
1/50 |
1/85 |
|
42 |
1/40 |
1/65 |
|
43 |
1/30 |
1/55 |
|
44 |
1/25 |
1/40 |
|
>45 |
1/20 |
1/30 |